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| Click here to select a new forum. | | Powerbook 100 AC adapter problem | Posted by: Wawavoun on 2022-07-04 11:43:31
Hello,
I try to repair a Powerbook 100 AC adapter.
I have change each chemical capacitors even on the daughter board.
All the measurements was done without load.
The problem is that I got only ~ 6.3 V at output with the voltage pot in max position.
The output voltage is not stable and move slowly from down to up at the beginning and then after 20-30 s from up to down.
At one moment the voltage stabilize to more or less 6,3 V, but not exactly the same value at each try.
There is not evidence of overheating or damage on the board and on the components.
I have not found schematics or valuable information (except for recap) on this adapter so I anybody can suggest a way to find and correct the problem ?
I have a second on adapter and this one give 7.7 V at output without load. The powerbook 100 works well with this adapter.
May be can I made some measurements on both but where to start ?
Regards.
Philippe
ps : | Posted by: Wawavoun on 2022-07-05 12:04:00
Hi,
I am answering myself.
Since the beginning I suspect a problem of current leakage somewhere.
I was suspicious against the old dielectric coming from the leaky chemical caps.
Even the welded connectors between main pcb and daughter board have been polluted by this sh... And my opinion is that this liquid come conductive when heated !
Yesterday evening I put a lot of iso propyl alcohol on all the pcb and in the connectors, then I drain the alcohol from the board just by gravity and let it dry 24 h.
Today evening everything works fine !
So be careful if this liquid come into small space with conductive parts. Partial conduction or short circuit are possible.
Regards.
Philippe | Posted by: Byrd on 2022-07-05 16:40:18
Good news Wawavoun; some Apple PSUs, power bricks I've come across the capacitor leakage is like honey and very difficult to remove without a thorough cleaning | | 1 |
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